1. Field of Disclosure
The present disclosure relates to a display apparatus and a method of controlling the same. More particularly, the present disclosure relates to a display apparatus having a backlight unit driven in a color dimming mode and a method of controlling the display apparatus.
2. Description of the Related Art
In recent years, various flat panel displays, such as a liquid crystal display, a plasma display panel, an organic light emitting diode display, etc., are mainly used as image display devices.
The liquid crystal display includes a display panel displaying an image through pixels arranged in a matrix form using optical and electrical properties of liquid crystal molecules, such as anisotropic refractive index and anisotropic dielectric constant, a driving circuit driving the display panel, and a backlight unit providing a light to the display panel. Each pixel of the liquid crystal display displays a grayscale by changing an alignment of the liquid crystal molecules in response to various signals, e.g., a gate signal, a data signal, a common voltage signal, etc., and controlling a light transmittance of the light generating from the backlight unit and passing through the display panel and a polarizing plate.
In the liquid crystal display, each pixel has a brightness determined by multiplying a brightness of the backlight unit by the light transmittance of the liquid crystal molecules. To improve a contrast ratio and reduce power consumption, the liquid crystal display uses a backlight dimming method that analyzes input image data and controls a dimming value to control the brightness of the backlight unit and to compensate for the data.
In recent, a light emitting diode (hereinafter, referred to as an LED) backlight unit employing LEDs is widely used as a light source of the backlight unit since the LED has advantages of high brightness and low power consumption when compared to a cold cathode fluorescent lamp.
The LED backlight unit is driven in a local dimming method that controls the brightness of specific block of the LED backlight unit after dividing a light emitting area of the light source of the LED backlight unit into plural blocks. The local dimming method divides the light emitting area of the LED backlight unit into the blocks, analyzes the data in accordance with the blocks, determines a local dimming value, and compensates for the data, and thus the contrast ratio is improved and the power consumption is reduced.
The LED backlight unit mainly uses a white LED emitting a white light, but an LED backlight unit emitting colored light includes at least two LEDs displaying different light colors of primary colors, i.e., red (R), green (G), and blue (B) color LEDs, to improve color reproducibility. The liquid crystal display employing the color LED backlight unit is operated in a color dimming method that individually analyzes R, G, and B image data and controls R, G, and B LEDs in each block, thereby reducing the power consumption and improving the color reproducibility.
In a case that the backlight unit, which is driven in the color dimming method, provides the light to pixels each including red (R), green (G), blue (B), and white (W) sub-pixels, the color reproducibility of each pixel is lowered. This is because a color filter for the white sub-pixel does not exist and the light provided to the white sub-pixel from the backlight unit is not sharpened. That is, a full-width-half-maximum (FWHM) of the light becomes wider and the light provided to the white sub-pixel exerts influence on other sub-pixels.
Accordingly, a control method of a display apparatus preventing deterioration of the color reproducibility, which is caused by applying the backlight unit driven in the color dimming method to a pixel having a pentile structure, is required.